While the problem is very real, I don't think it's the fault of abstractions or even developers. If you have to fight your product manager for the authorization to spend a little time using resources correctly, it is probably because there's no organization-wide incentive to reduce resource usage of a web application, unless you're called Apple, Google or Mozilla.

It’s a mix, probably. In some cases it’s organizational, it there’s absolutely also devs who take a cavalier attitude towards optimization.